[Bonmin] New stable branch and candidate for release

[Pierre Bonami]

Dear list,
Following Stefan (and others) gentle suggestion I think it is time to 
have a new release of Bonmin.
I have created a new stable branch 0.99 and made a new release 0.99.0.
I think that the code is mostly stable (and more stable than the last 
release 0.1.4). Nevertheless some more tests are needed and I think it 
is safer to call it a candidate release.

There are quite a few changes in this version almost all the code has 
been rewritten over the last year and a half (and some of the changes 
are not yet activated). I will try to document the changes as we move 
towards release 1.0. There is already a quite up-to-date option 
documentation available here:
http://www.coin-or.org/Bonmin/options_list/index.html
(note that some options names may have changed)

The main major change is that the default algorithm has been changed 
from B-Hyb to B-BB (i.e. outer-approximation to pure branch-and-bound). 
This is mostly for two reasons. First because we did a lot of work on 
B-BB and it is now a lot more efficient than it used to be. Second 
because many users were trying to solve non-convex problems with the 
default settings and B-Hyb gave them terribly bad results. Still on some 
convex problems B-Hyb or B-QG can be much faster than B-BB and if you 
find the default algorithm too slow you should try them by putting
bonmin.algorithm B-Hyb
in the bonmin.opt option file.

Another important change is that the default node selection strategy has 
been changed from best-bound to dynamic. This should have the good 
effect that feasible solutions are found faster but on the other hand it 
may take longer to prove optimality. Again you can use best-bound using 
the node_comparison option.

Cheers,
Pierre